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Abstract

Two independent but very similar mol­ecules comprise the asymmetric unit of the title compound, [Zn(C8H16NS2)2(C12H8N2)]. The N2S4 donor set about Zn is defined by two symmetrically chelating dithio­carbamate ligands and a 1,10-phenanthroline ligand. Distortions from the ideal octa­hedral coordination geometry arise from the restricted bite angles of the ligands. The main feature of the crystal packing is the formation of tetra­meric supra­molecular aggregates mediated by C—HS inter­actions. Disorder was found in each of the sec-butyl groups. This was resolved over two positions in each case with the major components of the disorder having site occupancies in the range 0.551 (6)–0.725 (5).

Acknowledgments

We thank UKM (UKM-GUP-NBT-08–27-111 and UKM-ST-06-FRGS0092–2010), UPM and the University of Malaya for supporting this study.

supplementary crystallographic
information

Comment

Dithiocarbamate anions (Howie et al., 2008) and their zinc
derivatives,
including their adducts with nitrogen-containing bases (Benson et al.,
2007), attract attention in crystal engineering endeavours. Often the
polynuclear structures found in the structures of the parent binary precursor
compounds are broken down in the presence of base. However, in the present
study, the parent binary compound Zn[S2N(sec-Bu)(n-Pr)]2
(Awang et al., 2010) was found to be mononuclear in its crystal
structure, an observation consistent with the influence of the relatively
large iso-butyl groups (Tiekink, 2003). Not surprisingly, its
1:1
1,10-phenanthroline adduct, (I), is also mononuclear.

The crystallographic asymmetric unit of (I) comprises two very similar
molecules, Figs 1 and 2. Each Zn atom is coordinated by two dithiocarbamate
ligands which form similar Zn–S bond distances, Table 1, with the range being
relatively narrow, i.e. 2.4881 (6) Å, for Zn2–S6, to 2.5311 (6) Å,
for Zn1–S2. Similarly, the Zn–N bond distances span a narrow range, Table 1.
The coordination geometry is based on an octahedron with deviations related to
the restricted bite distances of the chelating ligands.

The presence of C–H···S interactions, Table 1, lead to the formation of
tetrameric supramolecular aggregates in the crystal structure of (I). The S8
atom is pivotal in these. The molecules comprising the asymmetric unit are
connected by the C–H···S8 interaction involving the C28–H28a atom.
The dimeric aggregates thus formed are linked via the C–H···S8
interaction involving the C50–H50 atom, Fig. 3. Globally, the molecules pack
into layers parallel to (0 1 1) and inter-digitate, Fig. 4.

Experimental

Carbon disulfide (20 mmol) was dropped into an ethanol solution (100 ml) of
N-sec-butyl-N-n-propylamine (20 mmol). The
solution was kept at 273 K for an hour. Zinc chloride (10 mmol) dissolved in
ethanol (50 ml) was added to give a white precipitate. This was collected and
redissolved in chloroform (50 ml). The solution was mixed with a solution of
1,10-phenanthroline (10 mmol) dissolved in ethanol (10 mol). The yellow
solution was set aside for the growth of crystals.

Refinement

H-atoms were placed in calculated positions (C—H 0.95 to 1.00 Å) and were included in the refinement in the riding model approximation,
with Uiso(H) set to 1.2 to 1.5Uequiv(C).

All sec-butyl groups were found to be disordered. For each group, the
site occupancies were refined. The major component had site occupancy
factor of 0.551 (6) for the C5-containing group, 0.725 (5) for the C13-group,
0.587 (6) for the C33-group, and 0.557 (6) for the C41-group. For both the
ordered n-propyl and disordered sec-butyl groups, the
1,2-related C–C distances were tightly restrained to 1.500±0.005 Å and the
1,3-related ones to 2.51±0.01 Å. Within the S2C–NC2 fragment, the
S2C–N distances were restrained to 1.35±0.01 Å and the
N–Calkyl distances to 1.45±0.01 Å. Finally, all anisotropic
displacement parameters were refined individually except for the C33' and C36'
atoms which were refined isotropically. Additionally, the anisotropic
displacement parameters for the carbon atoms of both the ordered
n-propyl and disordered sec-butyl groups were tightly restrained
to be nearly isotropic.

The maximum and minimum residual electron density peaks of 1.32 and 0.59
eÅ-3, respectively, were located 0.50 Å and 0.28 Å from the
H36b
and C40 atoms, respectively.

Figures

The molecular structure of the first independent molecule in (I) showing the atom-labelling scheme and displacement ellipsoids at the 50% probability level. Only the major components of the disordered atoms associated with the sec-butyl groups are shown...

The molecular structure of the second independent molecule in (I) showing the atom-labelling scheme and displacement ellipsoids at the 50% probability level. Only the major components of the disordered atoms associated with the sec-butyl groups are shown...